Adjustable tuning apparatus for a radio



Feb. 8, 1966 L. w. M. SCHIJVEN ADJUSTABLE TUNING APPARATUS FOR A RADIO Filed April 15, 1964 FIG.1

INVENTOR.

MlflfT/NUS SCH IJVEN LUCAS WILHELMUS 3,233,469 ADJUSTABLE TUNING APPARATUS FOR A RADIO Lucas Wilhelmus Martinus Schijven, Emmasingel, Eindhoven, Netheriands, assignor to North American Phiiips Company, Inc., New York, N.Y., a corporation of Delaware Filed Apr. 13, 1964, Ser. No. 359,289 3 Claims. (Cl. 74l-10.33)

This invention relates to a tuning device for radio receivers with at least one push-button for adjusting the tuning member to one of a plurality of predetermined positions by means of a substantially semi-circular disc which is rotatably mounted on a tuning slide which is substantially strip-shaped and is operated by the pushbutton. The disc can be locked in any chosen position with respect to the tuning slide by means of a clamping lever journalled on said slide and extending in the longitudinal direction thereof. Said lever having an inclined portion cooperable with a separately slidable member provided on the tuning slide in order to clamp the edge of the semi-circular disc between the lever and the tuning slide, while unlocking of the disc is effected by withdrawing the separately slidabie member by pulling on the associated push-button.

A tuning device of this general description is known from U.S.P. 2,503,066.

It is an object of the invention to provide a device of .the said type, in which the fulcrum and the point of pressure of the lever are located very close to one another so that the required clamping force can be obtained with a comparatively small total length of the lever and in which the said total length substantially determines the length of the tuning slide thus achieving compactness. It is a further object of the invention to provide a device in which the construction of the tuning device consists of very few parts which can be assembled in a simple manner and at small cost.

According to the invention these objectives can be achieved in that the clamping lever has the form of a U with short inwardly bent limbs, which extend through apertures in the substantially strip-shaped tuning slide, and on which the fulcrum and, farthest remote from the push-button, the inclined portion of the lever are located. The clamping lever bridges the semi-circular disc and the bridging portion defines the point of pressure of the lever arm located near the fulcrum but between the fulcrum and the inclined portion.

An embodiment of the invention which deals in particular with said further object is characterized in that the separately slidabie member is constructed in the form of a strip which is bifurcated on both ends, one of the ends projecting into one groove-shaped recess in the pushbutton together with the adjacent end of the strip-shaped tuning slide. The slideable member being locked in the push-button by the resilient separation of the two teeth of the fork and also by means of lateral projections formed on at least one of the teeth of the fork. The other bifurcated end of the slideable member embracing the portion of the limb of the U-shaped lever which projects through the tuning slide and is provided with an inclined portion.

In order that the invention may readily be carried into effect, an embodiment thereof will now be described more fully, by way of example, with reference to the accompanying drawings, in which:

FIGURES 1 and 3 show bottom and top plan views respectively of a preferred embodiment of the invention and FIG. 2 shows a side elevation of this embodiment.

FIGURE 4 shows a cross-sectional view taken along the line IV-IV in FIGURE 2.

FIGURE 5 is a longitudinal cross-sectional view simi lar to FIG. 2 in another operative position.

The figures show only the part of a tuning device for a radio receiver which is essential to the invention in which a number of substantially strip-shaped tuning slides 3 (only one of them is shown) operated by a plurality of push-buttons 1 (only one shown). Slides 3 are journalled in a common frame 5 which may be of the normal construction and which is shown only in part. On each of the tuning slides 3 a substantially semi-circular disc 7 is rotatably provided around a short pivot 9 formed on the slide by depression. The disc 7 can be locked in any chosen angular position with respect to the tuning slide 3 by means of a clamping lever 11 journalled on said slide 3 and extending in the longitudinal direction thereof. Said lever 11 has the form of a U with a bottom arm portion and two short inwardly bent limbs 13 and 15 which extend through apertures 17 and M respectively in the strip-shaped tuning slide 3 (see FIGURE 2). In a manner to be described hereafter the clamping lever 11, 13, 15 is cooperable with a strip-shaped member 21 which is provided on the tuning slide 3 and is capable of sliding freely with respect to the slide 3 (see FIGURE 3) in order to clamp the edge of the semi-circular disc 7 between the lever 11 and the tuning slide 3. The disc 7 which is fixed or clamped in this manner in its adjusted position cooperates in known manner with a known frameshaped rotatable tuning member, that is, on pushing in the push-button 1 together with the tuning slide 3 (the pushed-in position is shown in broken lines in FIGURE 1) against the action of a spring (not shown) the edge of the disc 7, directed to the right in FIGURE 1, becomes located against the two parallel rods 22 of the rotatable frame (shown in broken lines in FIGURE 1), as a result of which the frame assumes a position which corresponds to the position of the disc 7, thereby bringing a tuning member of the receiver (not shown for clearness sake) in a predetermined desired position. The disc '7 can be adjusted to a different angular position after unlocking the clamping lever which is effected in a manner to be described below by withdrawing the separately slidable member 21 by pulling on the push-button. This unlocked position is shown in FIGURE 5.

As appears from a comparison of the FIGURES 2 and 5, the fulcrum 23 of the U-shaped clamping lever 11, 13, 15 is located on the inwardly bent limb 13 of the lever. The point of clamping pressure 25, that is to say the point where the lever presses against the edge of the disc '7 and holds it against the tuning slide 3, is located below fulcrum 23 but close to it. The other limb 15 of the U-shaped clamping lever, which limb, as is shown in FIGURES 2 and 5, is farthest remote from the pushbutton 1, has an inclined portion 27 which, as will appear from a comparison of FIGURES 2 and 5, is cooperable with the separately slidable strip-shaped member 21 and forms a stop at the right hand end of this member 21 so that further relative movement between member 21 and slide 3 is blocked and these two parts move as a unit further to the right (FIG. 2). This member 21 is forkshaped at each end (see FIGURE 3); the fork end shown on the right-hand side in the figures embraces the limb portion 15 of the clamping lever 11, 13, 15 in order to prevent the relative end of the member 21 and the limbportion 15 from becoming disengaged when member 21 is drawn out, by means of button 1, to the position in FIG. 5 so as to unclamp the disc 7 and the slide 3 by counterclockwise movement of lever 11.

FIGURE 2 shows the normal operative position of the lever 11 and associated parts. This position of the parts was achieved by a preceding depression of the pushbutton 1, whereby the strip-shaped member 21 was moved to the right with respect to the tuning slide 3 as compared with the position shown in FIGURE 5. During the relative sliding movement of member 21 relative to slide 3 the right-hand end of member 21 pushed along the inclined edge portion of lever 11, 13, 15, as a result of which the limb portion 15 swung the lever 11 about fulcrum 23 and elevated limb 15 as far as possible through the aperture 19. Because the fulcrum 23 and the point of pressure 25 of the clamping lever are located close to one another in the longitudinal direction thereof, which is possible as a result of the described shape of the lever, the force which is exerted in the point of pressure 25 by the lever, on the edge of the disc 7, can be considerable without a comparatively long arm portion of the lever 11 being required for that purpose. This length need hardly be greater than the length required for bridging the semi-circular disc 7. As a result of this bridging, all further parts of the slide construction, with the exception of the push-button 1, are located within the length of the lever 11, 13, 15, as a result of which this determines substantially the total length of the slide 3. It will be clear that owing to the described construction this total length can be as small as possible.

As already noted, the two ends of the separately slidable strip-shaped member 21 are bifurcated. The lefthand end of member 21 in the figures, together with the adjacent end of the strip-shaped tuning slide 3, projects in at least one and in the present case in two grooveshaped recesses 29 and 31 of the push-button 1 (see FIGURE 4). The member 21 is locked therein, in this case in the groove 29, by a resilient separation of the two teeth 33 and 35 of the relative bifurcated end. For this purpose the projections 37 and 39 formed on the tooth 33 become located in apertures or grooves 41 and 43 of the push-button 1 by virtue of the resilient separation of the teeth 33 and 35. The adjacent ends of the tuning slide 3 and of the slidable member 21 are connected in the push-button 1 in a manner such that the member 21 remains separately slidable.

The limb portion 15 of lever 11 ensures (see FIGURES 2 and that the other end of the strip-shaped member 21 remains against the tuning slide 3. In order to ensure this also in the unlocked condition (see FIGURE 5), a strip-shaped leaf spring 45 is provided, preferably between the arm portion of the U-shaped clamping lever 11 and the semi-circular disc 7. The ends of the said spring 45 engage in a resilient manner the ends of the arm portion of lever 11 and is connected to slide at a point located on the free end of a pivot 9 formed on the tuning slide 3 which pivot, as already explained, serves as the rotary shaft for the disc 7. This leaf spring 45 not only serves for holding the member 21 against the slide 3 as shown in FIGURE 5 but also to prevent the semi-circular disc 7 falling from the pivot 9. A further result of the force exerted on the lever 11, 13, 15 by the spring 45 in the proximity of the end 15 is that for sliding the member 21 with respect to the tuning slide 3, from the position shown in FIGURE 5, a certain force is required. As a matter of fact, this force must be greater than the force of the spring (not shown) which resets the tuning slide 3 in the rest position after depressing and releasing the pushbutton 1. This inequality is necessary, as is known, so that on choosing a new tuning position, starting from the position shown in FIGURE 5, by depressing the button 1, the member 21 and the slide 3 at first move together until the disc 7 abuts on the rods 22 (FIGURE 1) of the pivotable adjusting frame and is set in a given desired angular position by these rods. Only after the angular positioning of the disc 7 is effected may the disc be locked by further depression of the button 1 until the button and slides 3, 21 are in the position shown in FIGURES 13. The left-hand end of the leaf spring 45 is preferably bifurcated and embraces the adjacent ends of the arm portion of lever 11. The portion of the spring 45 joining the bifurcated part extends between the point of pressure 25 of the clamping lever and the oppositely located part of the disc 7. The advantage hereof is that the leaf spring 45 which is manufactured from steel, provides a wear plate which prevents the formation of depressions in the edge of the disc 7 if this disc itself is manufactured from a material softer than steel.

What is claimed is:

1. Adjustable tuning apparatus for a radio comprising a pair of juxtaposed relatively longitudinally movable slides having a push-button connected thereto at one end, a rotatable disc means connected to one of said slides for positioning a tuning frame of said radio, and means connected with said one slide for clamping said disc in a determined angular position relative to said one slide; said means comprising a clamping lever on one side of said one slide straddling said disc, said lever having a generally U shape, an inwardly bent limb at each end of said lever, said limbs extending to the opposite side of said one slide through aperture defining means in said one slide, one said limb defining'a fulcrum means of said lever and the opposite limb defining cam means for turning said lever about said fulcrum means, the other slide of said pair of slides engaging said cam means, and pressure means on said lever closely adjacent said fulcrum means for engaging and clamping said disc against rotary movement upon turning of said lever by said cam means.

2. Adjustable tuning apparatus-according to claim 1 wherein said other slide of said pair of juxtaposed slides comprises an elongated member having a bifurcated end portion, said bifurcated end portion of said elongated member containing said limb defining said cam means, the other end of said elongated member having means for connecting said elongated member and said pushbutton for pulling said elongated member relative to said one slide, and means defining an elongated slot in said elongated member containing the limb of said lever defining a fulcrum.

3. Adjustable tuning apparatus according to claim 1 with the addition of a strip-shaped leaf spring substantially within said U shaped clamping lever and fixed at the axis of rotation of said disc, each end of said leaf spring engaging said clamping lever, one end of said leaf spring having a bifurcation containing the limb of said lever defining said fulcrum and overlying said pressure means for providing a wear plate between said pressure means and said disc.

References Cited by the Examiner UNITED STATES PATENTS 2,930,241 3/1960 Roback 74l0.33 2,996,925 8/1961 Stamm 74-1033 3,086,401 4/1963 Horton 74-10.33

MILTON KAUFMAN, Primary Examiner. 

1. ADJUSTABLE TUNING APPARATUS FOR A RADIO COMPRISING A PAIR OF JUXTAPOSED RELATIVELY LONGITUDINALLY MOVABLE SLIDES HAVING A PUSH-BUTTOM CONNECTED THERETO AT ONE END, A ROTATABLE DISC MEANS CONNECTED TO ONE OF SAID SLIDES FOR POSITIONING A TUNING FRAME OF SAID RADIO, AND MEANS CONNECTED WITH SAID ONE SLIDE FOR CLAMPING SAID DISC IN A DETERMINED ANGULAR POSITION RELATIVE TO SAID ONE SLIDE; SAID MEANS COMPRISING A CLAMPING LEVER ON ONE SIDE OF SAID ONE SLIDE STRADDLING SAID DISC, SAID LEVER HAVING A GENERALLY U SHAPE, AN INWARDLY BENT LIMB AT EACH END OF SAID LEVER, SAID LIMB EXTENDING TO THE OPPOSITE SIDE OF SAID ONE SLIDE THROUGH APERTURE DEFINING MEANS IN SAID ONE SLIDE, ONE SAID LIMB DEFINING A FULCRUM MEANS OF SAID LEVER AND THE OPPOSITE LIMB DEFINING CAM MEANS FOR TURNING SAID LEVEL ABOUT SAID FULCRUM MEANS, THE OTHER SLIDE OF SAID PAIR OF SLIDES ENGAGING SAID CAM MEANS, AND PRESSURE MEANS ON SAID LEVER CLOSELY ADJACENT SAID FULCRUM MEANS FOR ENGAGING AND CLAMPING SAID DISC AGAINST ROTARY MOVEMENT UPON TURNING OF SAID LEVER BY SAID CAM MEANS. 